1. Field of the Invention
The present invention relates to a magnetic separation apparatus for separating magnetic materials from non-magnetic materials in a material flow.
2. Description of the Related Art
Magnetic separators are used in many processing industries to remove ferrous and para-magnetic contamination from products and production lines, particularly in grain, food and chemical industries. Such contamination may arise in the form of metal fragments, staples and nails from packaging, nuts and bolts from processing machinery, wear and tear from moving frictional parts, magnetic stone and/or rust which could potentially cause production machinery damage or product contamination.
Magnetic separators are available in the form of racks of magnetic bars (sometimes also called rods or tubes) that are pulled or pushed through cleaning glands. Such racks are generally large and relatively heavy, and require large forces to actuate. Thus, most magnetic grate separators with power assisted magnet cleaning, have either one relatively large pneumatic cylinder or two or more relatively small pneumatic cylinders that are adapted to operate in sync to move a rack of magnetic bars. The use of a single large cylinder to push or pull a grate magnet through a rack of cleaning glands from the front or rear increases the size and bulkiness of the machinery and requires more space, which may be unavailable or inefficient in a production plant. It is also typically difficult to correctly synchronise the actuation of two or more smaller cylinders to push or pull a grate magnet through a rack of cleaning glands, especially if unevenly distributed loads occur. If synchronicity is not achieved, the rack encounters different resistance on each side, which tends to cause a “walking” or jerking effect. Uneven or jerky actuation may also be caused by the condensation of hygroscopic products, such as sugar, on the bars of the rack.
U.S. Pat. No. 5,190,159 describes a magnetic separator which requires a front and rear walled ferrous magnetics discharge chamber and a cleaning mechanism in the form of an independent “floating” annular wiper bushing disposed on a magnetic bar. The annular wiper bushing is adapted to move with the magnetic bar on which it is disposed within the walls of the said fixed magnetics discharge chamber and to move relative to the bar and wipe ferrous material off the magnetic bar as the bar is moved through the said magnetics discharge chamber.
Other prior art requires an independent cleaning annular wiping bushing to be attached to a bulk head or to one wall of a fixed magnetics discharge chamber. Magnet cleaning is effected as the magnet is moved through the magnetics chamber or bulk head to which the wiper bushing is attached.
Although prior art provides a magnetic separator which is cylinder and piston actuated, the magnetic tube, rod or bars are independently connected to the cylinder and its conventional non magnetic shaft.
In other prior art such as NIPPON 06284070 or PROGLAVA FR2848128 (A1), magnetic separation occurs when material flow is in contact or close contact with a stationery sleeve or tube inside which the array of magnets is free to move slidingly. The inner magnets are distanced from the material contact surface by the sleeve plus the clearance between the sleeve and the inner magnets which reduces the available magnetic force. Cleaning is effected as the inner magnet is withdrawn past the baffle or other cleaning means imposed, or attached to the sleeve.
The present invention seeks to provide a magnetic separation apparatus which will overcome or substantially ameliorate at least some of the deficiencies of the prior art, or to at least provide an alternative.
The present invention seeks to provide a self contained magnetic separation module which in order to function as such including in a self cleaning manner, does not require any external, additional or separate means of actuation other than the components which comprise a shaft piston cylinder and shaft seal device known as a pneumatic or hydraulic cylinder.
The present invention seeks to provide a self cleaning self contained magnetic separation module as herein before described which in order to function as a self cleaning magnetic separator does not require shaft wiping glands or wiping means external to the essential components of the device known as a pneumatic or hydraulic cylinder.
The present invention seeks to provide a magnetic separation device which is simpler with less components and which incorporates features herein before described which provide improvements over prior art by eliminating the otherwise essential need for bulk head or front and rear walled magnetics chambers, thus reducing manufacturing cost and eliminating the need for conventional fixed bar centres as is common to prior art self cleaning and non self cleaning grate type magnets. The present invention contrives to introduce incremental rotation of each bar of a grate magnet system and to provide the means to withdraw and extend the or each magnet bar separately into and out of a product stream thereby providing a range of contingencies against tendency of difficult material to bridge over conventional prior art grate type magnetic separators.
Further, the present invention seeks to provide a means of self cleaning high powered magnetic separation which is not dependent on moving an array of magnets inside a sleeve or tube which is in contact with a material flow. Sleeves are essential to many quick or self cleaning grate type and single element separating magnets of prior art including the NIPPON or PROGLAVA inventions herein before mentioned. The use of sleeves is not desirable as magnetism decreases on “inverse square law”. The introduction of a sleeve for wear resistance or to permit magnet cleaning substantially reduces the potential flux density required for extraction of modern day magnetic contamination of concern such as fragments of low magnetic susceptibility, like work hardened SS fragments and magnetic stone. Therefore the present invention substantially increases the potential magnetic separation efficiency.
The present invention seeks to provide a modular and self contained, self powered high strength rare earth magnetic separation apparatus which is also readily adapted to housings of various configurations.
It is the object of the present invention to substantially overcome or at least ameliorate one or more of the prior art disadvantages or at least provide a useful alternative.
It is to be understood that, if any prior art information is referred to herein, such reference does not constitute an admission that the information forms a part of the common general knowledge in the art, in Australia or any other country.